KM - Where is the foundation?

[macadonald]

Morning Guys,

I've recently posted a couple of questions on the subject, but I'm about to start a rear extension and am having the plans drawn up as we speak. As half of what will be the extension is currently a 1960's single and flat roof extension, I thought I'd dig an inspection pit on the weekend to see how deep the existing foundations were. Much to my amazement, after removing a square of grass, I dug down about 3 inches, found a fair amount of crushed glass and the base of the footing, which does not appear to be sitting on anything other than the clay.

Any ideas what this is apart from being very shallow. Surely there are not any hidden piles. Raft perhaps? I know the guy we bought from was a builder/handy man all his life and he built it, so perhaps there is simply no foundation and as it's single skin, with the support in the floor slab?

Was just curious if anyone had any ideas. Be nice to know what to expect when I start demolition. To be honest, I'm partly relieved.

Untitled

• macadonald
• 9 Jul 2012
• 1

Untitled

• macadonald
• 9 Jul 2012
• 1

Untitled

• macadonald
• 9 Jul 2012
• 1

 

[^woody^]

It's on a slab, you can see that from the outside where it projects

 

[macadonald]

Woody,

Thanks for the quick response. Could you explain that a bit more please for my own benefit please. Is this likely to be a reinforced slab where the load is spread everywhere rather than onto a foundation. I did knock through the airbrick cover to take a look internally and it looks like the roof of this vent (which also accommodates central heating pipes is a smooth finished concrete, rather than slab, but that may just be the base of a precast piece of concrete to extend the air vent.

 

[^woody^]

Just one big square of concrete spreading the load, aka a raft. Whether it's reinforced or not won't be relevant to load spreading

 

[macadonald]

Great - sounds like that's goign to be a whole lot easier to remove than deep trench fill foundations..